Portion of a shoe midsole



FIG. 1 is a front perspective view of a portion of a shoe midsole showing my new design;

FIG. 2 is a rear perspective view thereof;

FIG. 3 is a side view thereof; and,

FIG. 4 is a rear view thereof.

The uneven broken lines immediately adjacent to the shaded region represent unclaimed boundaries of the design. The uneven broken lines showing the remainder of shoe are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a portion of a shoe midsole, as shown and described. 